Open AccessEffects of 4‐aminopyridine on action potentials generation in mouse sinoauricular node strips
Author(s) -
Golovko Vladimir,
Gonotkov Mikhail,
Lebedeva Elena
Publication year - 2015
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.12447
Subject(s) - repolarization , cardiac transient outward potassium current , electrophysiology , 4 aminopyridine , pacemaker potential , inhibitory postsynaptic potential , biophysics , patch clamp , tetrodotoxin , membrane potential , sinoatrial node , medicine , chemistry , cardiology , potassium channel , heart rate , biology , blood pressure
The physiological role of I to has yet to be clarified. The goal of this study is to investigate the possible contribution of the transient outward current ( I to ) on the generation of transmembrane action potentials ( AP s) and the sensitivity of mouse sinoauricular node ( SAN ) cells to a 4‐aminopyridine (4 AP ) as I to blocker. The electrophysiological identification of cells was performed in the sinoauricular node artery area ( n strips = 38) of the subendocardial surface using microelectrode technique. In this study, for the first time, it was observed that dependence duration of action potential at the level of 20% repolarization ( APD 20 ) level under a 4 AP concentration in the pacemaker SAN and auricular cells corresponds to a curve predicted by Hill's equation. APD 20 raised by 70% and spike duration of AP increased by 15–25%, when 4 AP concentration was increased from 0.1 to 5.0 mmol/L. Auricular cells were found to be more sensitive to 4 AP than true pacemaker cells. This was accompanied by a decrease in the upstroke velocity as compared to the control. Our data and previous findings in the literature lead us to hypothesize that the 4 AP ‐sensitive current participates in the repolarization formation of pacemaker and auricular type cells. Thus, study concerning the inhibitory effects of lidocaine and TTX on APD 20 can explain the phenomenon of the decrease in upstroke velocity, which, for the first time, was observed after exposure to 4 AP . Duration of AP at the level of 20% repolarization ( APD 20 ) under a 4‐ AP concentration 0.5 mmol/L in the true pacemaker cells lengthen by 60–70% with a control.